The report is
also available from the journal ‘Cryptologia’, vol13, no.3:

SECRET

HEADQUARTERS, ARMY SERVICE FORCES

OFFICE OF THE CHIEF SIGNAL OFFICER

WASHINGTON 25, D.C.

SPSIC-6
8
January 1945

MEMORANDUM
for Assistant. Chief of Staff, G-2

Subject:
Staff Study on OSS Cryptographic Plan

The enclosed
staff study is forwarded for your consideration and comment,

For the Chief
Signal Officer:

W, Preston Corderman

Colonel, Signal
Corps

Chiefs Signal Security Branch

1. Incl

Study on OSS
Cryptographic Plan

STAFF
STUDY ON OSS CRYPTOGRAPHIC PLAN

PROBLEM
PRESENTED

1. How may
the need of OSS for a high grade, high speed cryptographic system be satisfied?

FACTS BEARING
ON THE CASE

2. OSS has a
requirement for a high grade, high speed cryptographic system for the encipherment
and decipherment of secret traffic.

3. At the
present time OSS is using the Converter M-134-A (short title SIGMYC) to satisfy
this requirement.

4. Prior to 5
April 1944, eight (8) SIGMYC were issued to OSS.

5. The
Assistant Chief of Staff, G-2, authorized the issue of twenty-six (26) SIGMYC
to OSS by memorandum for Col. Corderman from Col. Clarke dated 5 April 1944, to
meet the expanding needs of that organization.

6. Since 5
April 1944, twenty-one (21) SIGMYC have been delivered to OSS. That
organization now holds twenty-nine (29) machines; five more are available for
issue.

7. In the
past OSS has used one universal set of rotors with SIGMYC. These rotors were
replaced once.

8. In
September 1944 OSS requested two new sets of rotors, one set to be used in
Europe and the other set in the Far East. Thirty-eight (38) sets of rotors
SIGRHAT (for use in the Far East) have been issued in compliance with that
request.

9.
Twenty-five (25) sets of rotors SIGSAAD (for use in Europe) have also been issued.

10.
Instructional documents associated with SIGMYC are "Operating Instructions
for Converter M-134 and M-134-A (Short title SIGKOC and ‘photographs and
Drawings of Converter M-134-A (short title SIGVYJ). No copies of these
publications are available for issue. This situation was caused by the
destruction of the instructional documents when Converters M-134-A were turned
in by Army holders.

11. Requests
are received for spare parts with each request for the issue of a SIGMYC. The
spare parts list always include rotor stepping solenoids. There are no rotor
stepping solenoids on hand in this agency. Three requests for these items have
not been fulfilled.

12. In accordance
with authorization of the Assistant Chief of Staff, G-2, 27 July 1944, one
SIGTOT room circuit was furnished OSS in Washington. Authorization did not
extend to the issuance of tapes for use with this equipment. Additional SIGTOT
circuits have been made available to OSS in Europe. That organization is procuring
additional tape punching equipment to meet the increased demand for tape. OSS
requested the loan of such equipment until they are prepared to fulfill their own
needs for tape. This branch is supplying OSS with sufficient tape until that
organization is self-supporting in this respect.

13. Four (4) SIGCUM
have been issued to OSS with the approval of the Assistant Chief of Staff, G-2,
28 April 1944. These machines were sent to OSS in North Africa to replace four
(4) SlGCUM which were loaned to OSS by NATO and subsequently recalled by the
latter organization.

14. Within
the past six (6) months the communications requirements of OSS have markedly
increased. The cryptographic requirements have expanded proportionately. The
rapid expansion is vividly illustrated by the strip cipher requirements of that
organization. In June 1944 SSA requested OSS to furnish a monthly quota of
desired material in order to adjust production schedules here. The monthly
quota of strip cipher systems needed is now larger than the total number of
strip systems issued to OSS over a period of twenty (20) months.

15. It is
believed that the OSS will request the five (5) remaining SIGMYC of the authorized
allotment of twenty-six (26) machines. Instructional documents are not
available for issue with these converters. The reprinting of these documents
presents a major reproduction job.

16. OSS
encounters an ever present maintenance problem since the machines are
constantly breaking down. It is believed that the time is not far distant when
it will be impossible to maintain the machines adequately,

17. In order
to provide new rotors in the future it will be necessary to have rotors
returned from the field by OSS for rewiring. Thus, a rotation process will be
established to meet new demands for rotors which will result in the wearing out
of the rotors within a relatively short time. It is noted that it would take
between one to two years to procure new rotors.

18. OSS is
now trying out a modification of the standard --text deleted -- device, which utilizes -*- --text deleted--. That organization is contemplating an
increase in the distribution of these --text
deleted – to include the standard --text
deleted – held by OSS, thus, permitting inter-communication between the two
machines. The cryptographic principle involved his been approved by the Signal
Security Agency. OSS plans to utilize the -*-
--text deleted-- for secret radio transmissions.

19. The question arises as to what other means
are available. The following items of equipment are considered:

a. SIGTOT

This system
provides adequate security but the scarcity of equipment and the difficultly of
providing sufficient quantities of one-time tape render its use impracticable.
In addition SIGTOT is not at present adapted to multi-holders of a common
system, which is an operational requirement

b. SIGABA

Under present policy, it would be necessary to
assign a crypt team with each machine in order to make them available to OSS.
This presents a problem of securing sufficient personnel which appears
insurmountable at the present time. Furthermore, the use of SIGABA as a
solution to this problem is not generally regarded with favor.

c. SIGCUM

The
communications and cryptographic problems of OSS are developing rapidly in the Far
East where traffic is transmitted largely by radio. Since SIGCUM may not be
employed for secret traffic transmitted by means of radio the use of this
machine would not provide a solution to the problem, Although SIGCUM would be a
satisfactory substitute for SIGMYC in Europe, a revision of the cryptographic
facilities of OSS in that area is not considered feasible at this time.

d. SIGFOY

This
converter provides adequate security to fulfill the need for a high grade
cryptographic system and is well adapted to multiple holders of a common
system. Since it is not a high speed system, it would not fulfill this
requirement.

e. SIGLASE

This system
would provide adequate security and speed to meet the outlined requirements.
However, since SIGLASE is still in the development stage and the expected date
of issue is unknown it is not the immediate answer to the OSS problem.

20. From the
point of view of this branch the problem could be most acceptably solved by
making Army facilities available to OSS. It is realized that the latter organization
would probably not be favorably disposed toward such a solution,

CONCLUSIONS

21. The
continued use of SIGMYC by OSS in the Far East will present maintenance and

distribution problems which will be virtually impossible to solve.

22. A
replacement for SIGMYC is needed.

23. SIGABA,
SIGCUM and SIGTOT are not completely acceptable substitutes.

24. SIGFOY
and SIGLASE would be a solution to the problem but since it will require from
six to nine months to manufacture the SIGLASE, it cannot be considered an
immediate solution.

25. It
appears that the only immediate solution to the problem is for OSS traffic to
be handled by Army cryptographic facilities.

RECOMMENDATIONS

26. That OSS
be requested to utilize Army cryptographic communications facilities where such
exist.

27. That OSS
use its own cryptographic communications facilities where Army facilities do
not exist.

28. That, at
such time as the equipment referred to in paragraph 27 becomes unserviceable,
service be maintained by those Army cryptographic facilities and/or equipments
as may then be available.